This is the direction of a celestial object, measured clockwise around the observer's horizon from north. So an object due north has an azimuth of 0°, one due east 90°, south 180° and west 270°. Azimuth and altitude are usually used together to give the direction of an object in the topocentric coordinate system.

Sometimes, south is used as the starting point for azimuth angles instead of north, but on the Heavens-Above web site, north is always the origin.

We sometimes include the nearest compass direction as an abbreviation to help clarify the azimuth angles value in degrees. Up to three letters are used and they represent azimuth angles in the following order;

Strict definitionThe azimuth of a point on the celestial sphere is defined as the angular distance measured towards the east, from north, along the astronomical horizon to the intersection of the great circle passing through the point and the astronomical zenith with the astronomical horizon.

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